I'm still waiting for it to arrive. I've been excited ever since I placed my order, so the waiting is killing me. I really hope the quality is good! This was the only place I found with gluten-free nail polish for adults - everywhere else had very child-friendly colours (bright pink, neon green, orange) and nothing I was looking for (clear, classic red, pale pink, etc). It was a bit frustrating.
I used doxycycline maybe 4 times a year, for a week or so at a time, for acne treatment. I've never had a gluten reaction, but it IS hard on the stomach and cause headaches, just like many antibiotics. I don't recall what brand I use, but my pharmacist checked for me and said it was gluten-free.
I eat gluten-free oats, but not by the bowlful. I use them in baking - cookies, granola bars, that sort of thing. So far I haven't reacted to them, though my stomach has so many issues that sometimes it's hard to tell. In any case, if you were thinking about eating some, I wouldn't recommend eating a huge amount until you know how your body will handle it.